Disease issue brassica crops

Asked January 18, 2016, 11:24 AM EST

I could really use some assistance here. I have been planting my veggies in my garden for close to 7 years now, and I have never rotated. I know I should, but I don't have the ease of doing so. I also recently adopted a 'no till' type of setup. I used to till my garden and furrow it every spring and winter and two years ago, I started putting mulch on it instead. I started with grass clippings and leaves, and recently switched to double ground municipal mulch. I have zero weeds right now. But, I have a serious issue with my brussel sprouts, broccoli and cabbage.

I don't recall having such problems in the past, but its possible. The first thing I noticed when I planted the transplants is that the leaves discolored in a couple of weeks. They turned a pink/purple color. Now, I have quite a bit of broccoli, but only a couple of heads of cabbage, no brussel sprouts....and this was all planted early october. The brussel sprouts and some cabbage have made zero growth in that time. Heavily stunted. I have attached a photo gallery of pictures to see if I can get some assistance.

My suspicion is black rot. I hope I am wrong. I do not see the black ring when I cut open their stems. I also checked the root structure and do not suspect club root.

My questions are:

Is it black rot?
If so, I need to rotate crops for 2 years I think. But how far away should the be from the infected area?
Can double ground mulch have caused this problem?


Thank you for any assistance.

Waller County Texas vegetables plant health

5 Responses

From your photos, it does not look like black rot. The symptoms on your photos along with your description sound more of a nutritional problem.
When using mulch, which is partially crushed/chipped woody material, there is often a need to add nutrients. As microbes break down the mulch, it often times ties up or utilized the nitrogenous compounds thus reducing what is available to the plants.
Your photo of the roots show that the roots are sparse. This could also explain the stunting of the plant and subsequent appearance of poor nutrition. At this stage, there is not much that you might be able to do to recover the crop. But note that in future, additional nutrition may be needed to compensate when using woody mulch materials. I would suggest a soil test prior to spring planting to get an assessment of the nutrient levels in your soils.
Getting a good start on the roots will help the plant to go a long way.
The practice of rotation is a good one to reduce/suppress possible disease issues.

Thank you very much for the help! That is most definitely good news if there is any to be had. I DID have a soil test done last year, and at the time, it showed that phosphorous was 'very high'. This did not occur to me until after I posted the question. TAMU suggestion was to use ONLY Nitrogen fertilizer, which I have done as best as possible. Is high phosphorous a contributor (or source) of this nutritional info? Don't high phosphorous levels limit the plants ability to absorb nutrients?

High P can contribute to the symptoms that you see (ie. margin scorching of older leaves etc..) However, those symptoms are somewhat generic making it difficult to diagnose.
In most case, an ample available P is needed to start new plants as P is often associated with root growth. However, too much can be not good as well as causing imbalance. The photo showing sparse roots is concerning because with the lack of roots, it means that the plant is unable to draw nutrients from the soil. Hence, your goal would be to try to figure out what is causing the lack of root growth. I do believe that nutrient imbalance have contributed to the poor health of the plants but I suspect there are other factors also came into play. If you kept a gardening journal, I would suggest look at planting time and temperatures profiles.

Good luck with future plantings.

I do keep a journal, but I did not note planting time. It was very similar to last year though with the exception of the weather. The notable different this year from last year at the time these were planted is that the temperatures were a lot hotter for a lot longer and we had a lot more rain. The other parameters is soil pH, which was tested at 7.8. Is that high enough to limit nutrient uptake?

Hot weather conditions can affect germination and seedling growth of cold weather crops. The function of soil pH and nutrient uptake is dependent on soil types. In your situation, it seems that the lack of root probably contributed most to the nutrient deficiency problem.
The following link to a chapter in the Texas Vegetable Growers Handbook may provide some helpful information as you continue growing. http://aggie-horticulture.tamu.edu/vegetable/guides/texas-vegetable-growers-handbook/chapter-iii-soi...